The invention relates to a heat exchanger in heating installations or an engine radiator of motor vehicles with the features of a double flow row arrangement of parallel flat tubes, which are connected to one another via zig zag fins, at least one water case with a tube bottom and a cap in communication with free ends of the tubes, the flat tubes have a double flow design by a tube partition extending longitudinally and engaging at the free end of the tubes a slit in the tube bottom common to both flows at both sides of the tube partition, the water case is divided into an inlet and an outlet, arranged at the plane of the tube partition, a header partition engages the groove or slit in the tube bottom and a groove in the cap thereby intersecting the free ends of the flat tubes, and the tube bottom or cap and the partition of the water case as well as the flat tubes and zig zag fins arc made of aluminum or an aluminum alloy. Such a heat exchanger is known from EP 0 656 517 A1.
In this known heat exchanger, the partition is soldered or brazed on the one hand into a groove at the cap of the water case and on the other hand into a groove or slit at the tube bottom or tube plate of the water case. It is also possible to alternately or in another group provide grooves at some spots, slits at other spots at the tube bottom to be soldered or brazed with the partition.
From U.S. Pat. No. 5,236,044, on the other hand a heat exchanger, preferably as liquefier or condenser, is known, in which a header which is rounded in order to take up the internal pressure is composed of two shells also rounded which receive a container subdivision between them. In this case, a soldered or brazed engagement with a shell for subdividing the container is effected by an engagement with a groove having at its ground at least one slit adapted to be gripped by a tongue of the container subdivision.
In both mentioned known cases, the interesting and subsequent soldering or brazing of the partition or the container subdivision, respectively, is effected by a direct manipulation at this partition or container subdivision, respectively. This is not only somewhat arduous, but it can also lead to undesired large brazing or soldering gaps in case of a not optimal engagement with the groove or the slit in the sense of the first mentioned publication or the combination of groove and slit in the sense of the second mentioned publication, which involves the risk of a leakage.